Reducing power consumption in voice over long term evolution terminals using semi persistent scheduling in connected discontinuous reception mode

ABSTRACT

A connection with a network that includes a base station (BS) may be established by a user device (UE) via a wireless connection, for conducting communications using semi persistent scheduling (SPS) in a connected discontinuous reception (C-DRX) mode. The SPS transmit periodicity may be adjusted with respect to the SPS activation command and the SPS interval UL (for uplink). Data may then be transmitted during the C-DRX On-Duration periods according to the determined SPS transmit periodicity. In some embodiments, the SPS transmit periodicity is adjusted such that following a first C-DRX On-Duration period when an SPS activation command is received, SPS data transmission occurs a specified number of subframes earlier during each subsequent C-DRX On-Duration period than in the first C-DRX On-Duration period. The SPS data transmission in each subsequent C-DRX On-Duration period may take place as soon as the UE device wakes up during the On-Duration period.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.14/153,675 titled “Reducing Power Consumption in Voice over LTETerminals using Semi Persistent Scheduling in Connected DiscontinuousReception Mode”, filed on Jan. 13, 2014, which itself claims benefit ofpriority of U.S. Provisional Patent Application Ser. No. 61/752,170titled “Reducing Power Consumption in Voice over LTE Terminals usingSemi Persistent Scheduling in Connected Discontinuous Reception Mode”,filed on Jan. 14, 2013, both of which are hereby incorporated byreference in their entirety as though fully and completely set forthherein.

FIELD OF THE INVENTION

The present application relates to wireless communication devices, andmore particularly to methods for saving power in a radio receiverimplemented in a wireless communications device.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. In recentyears, wireless devices such as smart phones and tablet computers havebecome increasingly sophisticated. In addition to supporting telephonecalls, many mobile devices now provide access to the internet, email,text messaging, and navigation using the global positioning system(GPS), and are capable of operating sophisticated applications thatutilize these functionalities. In general, wireless communicationtechnologies, such as cellular communication technologies, aresubstantially designed to provide mobile communication capabilities towireless devices generally powered by a portable power supply, e.g., abattery. Batteries hold a finite charge, and so in order to improvebattery life of wireless devices, one approach is to reduce powerconsumption required to perform wireless communications. Accordingly,some wireless communication technologies implement features designed toconserve power while still providing a high-quality user experience.Generally speaking, portions of circuitry in a wireless may be powereddown when not in use in order to save power and conserve battery life.

One significant consumer of power in a wireless device is transmitterand receiver circuitry (hereinafter ‘wireless circuitry’ or ‘transceivercircuitry’) that enables wireless communications. One example of a powersaving technique developed to save power in transceiver circuitry isknown as discontinuous reception (or DRX). In devices utilizing DRX,portions of wireless circuitry may be powered down if there is noinformation (e.g., packets) to be received or transmitted. The wirelesscircuitry may periodically be powered on to determine if there isinformation to be received, and subsequently powered back down again ifsuch a determination indicates that no new information is incoming. Adevice utilizing DRX may determine from a header in a transmitted packetif the information contained therein is incoming for that device. If theinformation is not relevant to that device, then circuitry may bepowered down for at least a portion of the remainder of the packet, andsubsequently powered on before the next header. Polling is anothertechnique that may be used, wherein a device may periodically send abeacon to an access point or base station to determine if there is anyinformation waiting for reception. If no information is awaitingreception, portions of the wireless circuitry may be powered down untilthe next beacon is to be transmitted. In addition to determining ifinformation is awaiting reception by the mobile device, neighbor cellsearching may be conducted during the time when the wireless circuitryis powered up while operating in a DRX mode. Neighbor cell searching maybe performed in order to enable cell reselection and handover of themobile device from one cell to another.

In general, DRX has been introduced in several wireless standards suchas UMTS (Universal Mobile Telecommunications System), LTE (Long-termevolution), WiMAX, etc., which powers down most of user equipment (UE)circuitry when there are no packets to be received or transmitted, andonly wakes up at specified times or intervals to listen to the network.DRX can be enabled in different network connection states, includingconnected mode and idle mode. In connected DRX (C-DRX) mode, the UElistens to the downlink (DL) packets following a specified patterndetermined by the base-station (BS). In idle DRX (I-DRX) mode, the UElistens to the page from the BS to determine if it needs to reenter thenetwork and acquire the uplink (UL) timing. Because DRX allows the UE toswitch off its transceiver circuitry for short intervals when there isno data to receive or transmit, and start “wake up and sleep” cycles tocheck whether there is data to send or receive, operating in C-DRX modehelps decrease battery usage.

Another aspect of wireless data transmission is scheduling. In mostcases, scheduling is fully dynamic. In a downlink direction, resourcesare assigned when data is available. For data to be sent in the uplinkdirection, the UE dynamically requests transmission opportunitieswhenever data arrives in the UE's uplink buffer. Information about databeing sent in the downlink direction, and uplink transmissionopportunities are carried in the radio layer control channel, which issent at the beginning of each subframe. While dynamic scheduling isefficient for infrequent and bandwidth consuming data transmissions,which may result in large data bursts (e.g. web surfing, videostreaming, emails), it is less suited for real time streamingapplications such as voice calls. In the latter cases, data is sent inshort bursts at regular intervals. If the data rate of the stream isvery low, as is the case for voice calls, the overhead of the schedulingmessages can become very high, as only little data is sent for eachscheduling message.

One solution to this issue has been semi-persistent scheduling (SPS).Instead of scheduling each uplink or downlink transmission, atransmission pattern is defined instead of single opportunities. Thissignificantly reduces the scheduling assignment overhead. During silenceperiods, the wireless voice CODECs in UEs stop transmitting voice data,and only send silence description information with much longer timeintervals in between. During those times of silence the persistentscheduling can be switched-off. In the uplink, the SPS grant scheme isimplicitly canceled if no data is sent for a network-configured numberof empty uplink transmission opportunities. In downlink direction, SPSis canceled with an RRC (Radio Resource Control) message. While C-DRXoffers a way to save battery power, and SPS offers a way to reducescheduling overhead, there is room for further improving the performanceand power consumption voice over LTE (VoLTE) terminals.

SUMMARY OF THE INVENTION

Embodiments described herein relate to a User Equipment (UE) device andassociated method for saving power in a radio receiver implemented in awireless communications device. A connection with a network thatincludes a base station may be established via a wireless connection.The communication may take place using semi persistent scheduling (SPS)in a connected discontinuous reception (C-DRX) mode. The SPS transmitperiodicity may be adjusted with respect to the SPS activation commandand the SPS interval UL (for uplink). Data may then be transmittedduring the C-DRX On-Duration periods according to the determined SPStransmit periodicity. In some embodiments, the SPS transmit periodicityis adjusted such that following a first C-DRX On period when an SPSactivation command is received, SPS data transmission occurs 4 subframesearlier during each subsequent C-DRX On-Duration period than in thefirst C-DRX On-Duration period. That is, SPS data transmission in eachsubsequent C-DRX On-Duration period may take place as soon as the UEdevice wakes up during the On-Duration period.

In some embodiments, there may be multiple subframes in a C-DRXOn-Duration period, and due to loading, the network may prefer the UE totransmit at some other subframe in the C-DRX On-Duration period ratherthan at the first subframe in the C-DRX On-Duration period. The Networkmay inform the UE of this preference in the form of anSPS-Activation-Offset parameter through UE higher layer signaling suchas RRC. The SPS-Activation-Offset may be applied after the SPS transmitperiodicity has been adjusted based on the SPS activation command andthe SPS interval UL, as set forth above. The SPS-Activation-Offset maybe expressed in terms of subframes (e.g. 1 ms in certain embodiments),and the actual SPS transmission may take place as determined by thenewly adjusted SPS transmit periodicity (based on the previouslyadjusted SPS transmit periodicity and the SPS-Activation-Offset) afterthe UE wakes up for the C-DRX On-Duration period. In some embodiments,the newly adjusted SPS transmit periodicity may take on the value of:the previously adjusted SPS transmit periodicity+SPS-Activation-Offset.

Accordingly, a wireless user equipment (UE) device may include a radiohaving one or more antennas for performing wireless communication, and aprocessing element coupled to the radio and capable of adjusting a semipersistent scheduling (SPS) transmit periodicity with respect to an SPSactivation command and SPS interval. The radio and the processingelement may interoperate to establish a connection with a network via awireless link, communicate with the network via the wireless link usingconnected-mode discontinuous reception (C-DRX) and SPS, and transmitdata during C-DRX On-Duration periods, beginning each data transmissionat a respective point in time determined according to the adjusted SPStransmit periodicity. The processing element may also be capable ofadjusting the SPS transmit periodicity to cause the radio and theprocessing element to begin transmitting data as soon as the UE wakes upduring a C-DRX On-Duration period. The radio and the processing elementmay also interoperate to begin transmitting data a specified number ofsubframes following reception of an SPS activation command during aC-DRX On-Duration period when the SPS activation command is received.

In some embodiments, the processing element may readjust the SPStransmit periodicity according to the adjusted SPS transmit periodicityand an SPS Activation Offset value. The radio and the processing elementmay further interoperate to receive, as part of communication with thenetwork via the wireless link, the SPS Activation Offset value from thenetwork, and also receive the SPS Activation Offset value through higherlayer signaling.

According to various embodiments, a method for reducing powerconsumption in a wireless UE device may include

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem;

FIG. 2 illustrates a base station in communication with a wireless userequipment (UE) device;

FIG. 3 illustrates an exemplary block diagram of a UE, according to oneembodiment;

FIG. 4 illustrates an exemplary block diagram of a base station;

FIG. 5 is timing diagram illustrating general operations of a C-DRXcapable UE over a period of time;

FIG. 6 is a timing diagram illustrating SPS data transfer whileoperating in C-DRX mode, according to one embodiment;

FIG. 7 is a timing diagram illustrating SPS data transfer whileoperating in C-DRX mode, according to another embodiment;

FIG. 8 is a flowchart diagram illustrating a method for configuring SPSand C-DRX to reduce power consumption in VoLTE terminals, according toone embodiment; and

FIG. 9 is a flowchart diagram illustrating a method for configuring SPSand C-DRX to reduce power consumption in VoLTE terminals, according toanother embodiment.

While features described herein are susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to be limiting to the particular form disclosed, but onthe contrary, the intention is to cover all modifications, equivalentsand alternatives falling within the spirit and scope of the subjectmatter as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Acronyms

Various acronyms are used throughout the present application.Definitions of the most prominently used acronyms that may appearthroughout the present application are provided below:

BLER: Block Error Rate (same as Packet Error Rate)

BER: Bit Error Rate

BS: Base Station

C-DRX: Connected Discontinuous Reception

CRC: Cyclic Redundancy Check

DL: Downlink

DRX: Discontinuous Reception

GSM: Global System for Mobile Communication

LTE: Long Term Evolution

PDCCH: Physical Downlink Control Channel

PDSCH: Physical Downlink Shared Channel

PER: Packet Error Rate

PUCCH: Physical Uplink Control Channel

PUSCH: Physical Uplink Shared Channel

SFN: System Frame Number

SINR: Signal to Interference-and-Noise Ratio

SIR: Signal to Interference Ratio

SNR: Signal to Noise Ratio

SPS: Semi Persistent Scheduling

Tx: Transmission

UE: User Equipment

UL: Uplink

UMTS: Universal Mobile Telecommunication System

VoLTE: Voice over LTE

Terms

The following is a glossary of terms that may appear in the presentapplication:

Memory Medium—Any of various types of memory devices or storage devices.The term “memory medium” is intended to include an installation medium,e.g., a CD-ROM, floppy disks 104, or tape device; a computer systemmemory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM,Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media,e.g., a hard drive, or optical storage; registers, or other similartypes of memory elements, etc. The memory medium may comprise othertypes of memory as well or combinations thereof. In addition, the memorymedium may be located in a first computer system in which the programsare executed, or may be located in a second different computer systemwhich connects to the first computer system over a network, such as theInternet. In the latter instance, the second computer system may provideprogram instructions to the first computer system for execution. Theterm “memory medium” may include two or more memory mediums which mayreside in different locations, e.g., in different computer systems thatare connected over a network.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System (or Computer)—any of various types of computing orprocessing systems, including a personal computer system (PC), mainframecomputer system, workstation, network appliance, Internet appliance,personal digital assistant (PDA), television system, grid computingsystem, or other device or combinations of devices. In general, the term“computer system” can be broadly defined to encompass any device (orcombination of devices) having at least one processor that executesinstructions from a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, Play Station Portable™, Gameboy Advance™,iPhone™), laptops, PDAs, portable Internet devices, music players, datastorage devices, or other handheld devices, etc. In general, the term“UE” or “UE device” can be broadly defined to encompass any electronic,computing, and/or telecommunications device (or combination of devices)which is easily transported by a user and capable of wirelesscommunication.

Base Station (BS)—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements. Processing elements include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem. It is noted that the system of FIG. 1 is merely one example of apossible system, and embodiments may be implemented in any of varioussystems, as desired.

As shown, the exemplary wireless communication system includes a basestation 102 which communicates over a transmission medium with one ormore user devices 106-1 through 106-N. Each of the user devices may bereferred to herein as a “user equipment” (UE) or UE device. Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station 102 may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UEs 106A through 106N. The base station 102 may also be equipped tocommunicate with a network 100 (e.g., a core network of a cellularservice provider, a telecommunication network such as a public switchedtelephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102 may facilitate communicationbetween the user devices and/or between the user devices and the network100. The communication area (or coverage area) of the base station maybe referred to as a “cell.”

The base station 102 and the user devices may be configured tocommunicate over the transmission medium using any of various radioaccess technologies (RATs), also referred to as wireless communicationtechnologies, or telecommunication standards, such as GSM, UMTS (WCDMA),LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD,eHRPD), Wi-Fi, WiMAX etc.

UE 106 may be capable of communicating using multiple wirelesscommunication standards. For example, a UE 106 might be configured tocommunicate using either or both of a 3GPP cellular communicationstandard (such as LTE) or a 3GPP2 cellular communication standard (suchas a cellular communication standard in the CDMA2000 family of cellularcommunication standards). Thus in some embodiments, the UE 106 might beconfigured to communicate with base station 102 according to a firstcellular communication standard (e.g., LTE) and might also be configuredto communicate with other base stations according to a second cellularcommunication standard (e.g., one or more CDMA2000 cellularcommunication standards). Base station 102 and other similar basestations operating according to the same or a different cellularcommunication standard may thus be provided as one or more networks ofcells, which may provide continuous or nearly continuous overlappingservice to UE 106 and similar devices over a wide geographic area viaone or more cellular communication standards.

The UE 106 might also or alternatively be configured to communicateusing WLAN, Bluetooth, one or more global navigational satellite systems(GNSS, e.g., GPS or GLONASS), one and/or more mobile televisionbroadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106-1through 106-N) in communication with the base station 102. The UE 106may be a device with wireless network connectivity such as a mobilephone, a hand-held device, a computer or a tablet, or virtually any typeof wireless device. The UE 106 may include a processor that isconfigured to execute program instructions stored in memory. The UE 106may perform any of the method embodiments described herein by executingsuch stored instructions. Alternatively, or in addition, the UE 106 mayinclude a programmable hardware element such as an FPGA(field-programmable gate array) that is configured to perform any of themethod embodiments described herein, or any portion of any of the methodembodiments described herein. The UE 106 may be configured tocommunicate using any of multiple wireless communication protocols. Forexample, the UE 106 may be configured to communicate using two or moreof CDMA2000, LTE, LTE-A, WLAN, or GNSS. Other combinations of wirelesscommunication standards are also possible.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols. In some embodiments, the UE106 may share one or more parts of a receive chain and/or transmit chainbetween multiple wireless communication standards. The shared radio mayinclude a single antenna, or may include multiple antennas (e.g., forMIMO) for performing wireless communications. Alternatively, the UE 106may include separate transmit and/or receive chains (e.g., includingseparate antennas and other radio components) for each wirelesscommunication protocol with which it is configured to communicate. Asanother alternative, the UE 106 may include one or more radios which areshared between multiple wireless communication protocols, and one ormore radios which are used exclusively by a single wirelesscommunication protocol. For example, the UE 106 may include a sharedradio for communicating using either of LTE or CDMA2000 1xRTT, andseparate radios for communicating using each of Wi-Fi and Bluetooth.Other configurations are also possible.

FIG. 3—Exemplary Block Diagram of a UE

FIG. 3 illustrates an exemplary block diagram of a UE 106. As shown, theUE 106 may include a system on chip (SOC) 300, which may includeportions for various purposes. For example, as shown, the SOC 300 mayinclude processor(s) 302 which may execute program instructions for theUE 106 and display circuitry 304 which may perform graphics processingand provide display signals to the display 340. The processor(s) 302 mayalso be coupled to memory management unit (MMU) 340, which may beconfigured to receive addresses from the processor(s) 302 and translatethose addresses to locations in memory (e.g., memory 306, read onlymemory (ROM) 350, NAND flash memory 310) and/or to other circuits ordevices, such as the display circuitry 304, radio 330, connector I/F320, and/or display 340. The MMU 340 may be configured to perform memoryprotection and page table translation or set up. In some embodiments,the MMU 340 may be included as a portion of the processor(s) 302.

As shown, the SOC 300 may be coupled to various other circuits of the UE106. For example, the UE 106 may include various types of memory (e.g.,including NAND flash 310), a connector interface 320 (e.g., for couplingto the computer system), the display 340, and wireless communicationcircuitry (e.g., for LTE, LTE-A, CDMA2000, Bluetooth, Wi-Fi, GPS, etc.).The UE device 106 may include at least one antenna, and possiblymultiple antennas, for performing wireless communication with basestations and/or other devices. For example, the UE device 106 may useantenna 335 to perform the wireless communication. As noted above, theUE may be configured to communicate wirelessly using multiple wirelesscommunication standards in some embodiments.

As described further subsequently herein, the UE 106 may includehardware and software components for implementing a method forperforming C-DRX cycle scaling. The processor 302 of the UE device 106may be configured to implement part or all of the methods describedherein, e.g., by executing program instructions stored on a memorymedium (e.g., a non-transitory computer-readable memory medium). Inother embodiments, processor 302 may be configured as a programmablehardware element, such as an FPGA (Field Programmable Gate Array), or asan ASIC (Application Specific Integrated Circuit). Furthermore,processor 302 may be coupled to and/or may interoperate with othercomponents as shown in FIG. 3, to reduce power consumption in VoLTEterminals using SPS in C-DRX mode, as will be further described below inthe section “Saving Power for VoLTE Terminals”.

FIG. 4—Exemplary Block Diagram of a Base Station

FIG. 4 illustrates an exemplary block diagram of a base station 102. Itis noted that the base station of FIG. 4 is merely one example of apossible base station. As shown, the base station 102 may includeprocessor(s) 404 which may execute program instructions for the basestation 102. The processor(s) 402 may also be coupled to memorymanagement unit (MMU) 440, which may be configured to receive addressesfrom the processor(s) 402 and translate those addresses to locations inmemory (e.g., memory 460 and read only memory (ROM) 450) or to othercircuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2. The network port470 (or an additional network port) may also or alternatively beconfigured to couple to a cellular network, e.g., a core network of acellular service provider. The core network may provide mobility relatedservices and/or other services to a plurality of devices, such as UEdevices 106. In some cases, the network port 470 may couple to atelephone network via the core network, and/or the core network mayprovide a telephone network (e.g., among other UE devices serviced bythe cellular service provider).

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The at least one antenna 434 may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UE devices 106 via radio 430. The antenna 434communicates with the radio 430 via communication chain 432.Communication chain 432 may be a receive chain, a transmit chain orboth. The radio 430 may be configured to communicate via variouswireless telecommunication standards, including, but not limited to,LTE, LTE-A WCDMA, CDMA2000, etc. The processor 404 of the base station102 may be configured to

implement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof.

DRX

The parameters for DRX cycles may be configured by the BS throughdifferent timers. The DRX inactivity timer indicates the time in numberof consecutive subframes to wait before enabling DRX. Short DRX cyclesand long DRX cycles are defined to allow the BS to adjust the DRX cyclesbased on the applications. In generation, a DRX short cycle timer may bedefined to determine when to transition to the long DRX cycle. Whenthere is no reception of packets for an extended period of time afterthe successful reception of a packet, the BS may initiate RRC connectionrelease and the UE may enter the RRC IDLE state, during which the idleDRX can be enabled. The On-Duration timer may be used to determine thenumber of frames over which the UE will read the DL control channelevery DRX cycle before entering power saving mode. The allowed valuesare 1, 2, 3, 4, 5, 6, 8, 10, 20, 30, 40, 50, 60, 80, 100, and 200.During idle DRX mode, the UE may monitor one paging occasion (PO) perDRX cycle, which is one subframe.

FIG. 5 illustrates various aspects of general C-DRX operation. Asindicated by 602, the UE 106 may operate in an active state and mayperform one or more uplink and/or downlink (UL/DL) transmissions (e.g.,transmit uplink data and/or receive downlink data). At 604, aninactivity timer may be initiated. The inactivity timer may be initiatedat the end of the active transmissions in 602. Note that the inactivitytimer may have been initiated one or more times during the activetransmissions in 6502, but may have been reset each time as a result ofcontinuing activity (transmissions) until no more activity was observedat 604, at which point it may run until expiration at 608. Theinactivity timer may have any length, as desired; some examples ofpossible inactivity timer length might include 100 ms, 80 ms, 50 ms, 40ms, or any other value, e.g., as specified by the 3GPP 36.331specification.

In 606, between initiation (at 604) and expiration (at 608) of theinactivity timer, the UE 106 may not be performing any uplink ordownlink transmissions, but may continue to operate in the active state,and may monitor one or more communication channels (e.g., a PDCCH) fordownlink grants. At 608, the inactivity timer may expire. At this pointthe UE 106 may transition to a reduced-power state (DRX), as a result ofhaving observed a sufficient period of data communication inactivity(e.g., as indicated by the expiration of the inactivity timer). Duringthe period of time that the UE 106 is operating in the reduced-powerstate, the UE 106 may power down and/or reduce power to one or morecomponents, such as baseband logic components and/or radio components.

At 610, the UE 106 may “wake-up” and re-enter the active state. The UE106 may wake up at a time specified by a schedule, e.g., of which it maybe informed by a base station (e.g., an eNode-B, in LTE). At thespecified time (or after a specified interval), the base station maynotify the UE 106 of a downlink grant for the UE 106, if there is anydownlink data pending, so the UE 106 may check (e.g., monitor acommunication channel such as a PDCCH) for downlink grants during thistime. One or more other functions may also be performed during thistime, if desired. This time period may also be referred to as the“on-duration” in C-DRX operation. According to some embodiments, theon-duration may last a specified length of time, such as 5 ms, or 10 ms,or another length of time, e.g., as specified by the 3GPP 36.331specification; alternatively, the on-duration may last until certainfunctions have been performed, and may end when no further specifiedfunctions need to be performed. At 612, the on-duration may end, and ifno downlink grants were received during the on-duration, the UE 106 maygo back to “sleep” and transition back into the reduced-power state. Anynumber of subsequent cycles of sleeping (DRX) and waking (on-duration)may be performed, as desired.

Note that the UE 106 may also be configured to transition between C-DRXcycles with different lengths. For example, as shown, the UE 106 mayperform up to a pre-determined number (such as 2, 4, 8, 16, etc.) of“short C-DRX” cycles 614 (which may last 20 ms, 40 ms, 80 ms, or anyother length of time), and if no uplink or downlink transmission areperformed by the end of the pre-determined number of cycles, the UE 106may perform one or more “long C-DRX” cycles 616 (which may last 80 ms,160 ms, 320 ms, or any other length of time, e.g., as specified by 3GPP36.331), which may specify a longer period of reduced-power stateoperation before waking up for active state on-duration operations. Thelong C-DRX cycles may continue until further active communication (e.g.,which may be initiated either by the UE 106 or the network) occurs, orone or more other conditions occur which might cause the UE 106 totransition away from the long C-DRX cycles.

If active communications are again initiated at some subsequent time,the UE 106 may perform similar steps (e.g., monitoringactivity/inactivity via an inactivity timer and initiating one or moreC-DRX cycles if sufficient inactivity is seen between activecommunications) if appropriate, e.g., depending on communicationactivity.

Saving Power for VoLTE Terminals

Communication, for example between a UE and a BS may occur in C-DRX modeusing SPS. FIG. 6 shows a timing diagram illustrating SPS data transferwhile operating in C-DRX mode, according to one embodiment. As seen inFIG. 6, at first the UE may be in Sleep mode (634) during C-DRXoperation, until it receives an SPS Activation command (328) during theC-DRX On-Duration period (636). This causes the UE to wake up (626), inother words, causes the UE to transition to a Talk state from a Listenstate. As shown in FIG. 6, the UE starts the SPS data transfer 4subframes later (630). However, the timing scheme illustrated in FIG. 6may result in extra long wake-up times (maximum of 4 subframes) duringthe C-DRX On-Duration (636) when the UE does not send voice data due toSPS periodicity, during the upload cycle (640). In other words, once theSPS activation command (628) has been received, during each subsequentC-DRX On-Duration period the UE may not start the SPS data transfer(632) until 4 subframes (638) following the start of the C-DRXOn-Duration period (636). It would be desirable to start transmission assoon as the UE or device wakes up (626) during the C-DRX On-Durationperiod (636).

FIG. 7 is a timing diagram illustrating SPS data transfer whileoperating in C-DRX mode, according to another embodiment, in whichtransmission is not delayed in each C-DRX On-Duration period, therebyreducing power consumption. As seen in FIG. 7, at first the UE may be inSleep mode (734) during C-DRX operation, until it receives an SPSActivation command (728) during the C-DRX On-Duration period (736),similar to what is shown in FIG. 6. This again causes the UE to wake up(726), and transition to a Talk state from a Listen state. Thus, UEstarts the SPS data transmission (SPS Tx) four subframes later (730).However, as shown in FIG. 7, subsequent SPS data transmission isimplicitly shifted by 4 subframes with respect to the SPS Interval UL(uplink) C-DRX cycle (732) to allow immediate transmission of data assoon as the UE or device wakes up during the C-DRX On-Duration over thecourse of the SPS Interval UL C-DRX cycle (740). That is, the SPS GrantPeriodicity may be implicitly adjusted to be four subframes less thanthe actual duration of the SPS Interval UL C-DRX cycle (740). The SPStransmit periodicities may therefore be expressed with respect to theSPS activation command, with the exception of the first SPS transmission(730), when the SPS activation command (728) is received.

Accordingly, in one set of embodiments, after a Semi-Persistent uplinkassignment is configured, the UE may consider that the grant recurs ineach subframe for which: (10*SFN+subframe)=[(10*SFNstart time+subframestart time)+(N*SPS Interval UL)−4] modulo 10240, for all N>0. Thisestablishes the SPS transmit periodicity with respect to the SPSActivation command. The “SFNstart time” and “subframe start time”represent the SFN and subframe, respectively, at the time the configureduplink grant was (re)initialized.

FIG. 8 shows a flowchart diagram illustrating one embodiment of a methodfor wireless communication that uses SPS in C-DRX mode, and reducespower consumption in VoLTE terminals. A UE may establish a connectionwith a network that may include a BS, via a wireless link (802). The UEmay configure itself to operate in C-DRX mode and use SPS (804). As partof the SPS in C-DRX mode, the UE may adjust the SPS transmit periodicitywith respect to the SPS activation command and the SPS Interval UL(806). Specifically, the UE may adjust the SPS transmit periodicity toallow SPS data transmission to commence as soon as the UE wakes upduring each C-DRX On-Duration period, with the exception of a firstC-DRX On-Duration period during which the UE receives the SPS activationcommand. The UE may therefore transmit data during C-DRX On-Durationperiods according to the adjusted SPS transmit periodicity (808).

In one set of embodiments, after a Semi-Persistent uplink assignment isconfigured, the UE may consider that the grant recurs in each subframefor which: (10*SFN+subframe)=[(10*SFNstart time+subframe starttime)+(N*SPS Interval UL)−4+SPS-Offset-Activation] modulo 10240, for allN>0. The “SFNstart time” and “subframe start time” again represent theSFN and subframe, respectively, at the time the configured uplink grantwas (re-)initialised. The network may communicate, i.e. configure theSPS-Offset-Activation at the UE through higher layer signaling, such asRCC, for example.

FIG. 9 shows a flowchart diagram illustrating one embodiment of a methodfor wireless communication that uses SPS in C-DRX mode, and reducespower consumption in VoLTE terminals by having a network communicate anSPS Offset Activation value to a UE through higher layer signaling. A UEmay establish a connection with a network that may include a BS, via awireless link (902). The UE may configure itself to operate in C-DRXmode and use SPS (904). As part of the SPS in C-DRX mode, the UE maycalculate the SPS transmit periodicity with respect to the SPSactivation command and the SPS Interval UL (906), in a manner similar towhat is shown in 806 of the flowchart diagram of FIG. 8. However, thenetwork may prefer the UE to transmit at some other subframe in theC-DRX On-Duration period rather than at the first subframe in the C-DRXOn-Duration period due to a variety of reasons. For example, there maybe multiple subframes in a C-DRX On-Duration period, and the network mayprefer the UE to transmit at another frame in the C-DRX On-Durationperiod due to loading. The UE may therefore further adjust the SPStransmit periodicity based on the previously adjusted SPS transmitperiodicity and an SPS Activation Offset parameter (908). In someembodiments, the network may communicate the value of the SPS ActivationOffset parameter through higher layer signaling, e.g. through RCC. TheUE may therefore transmit data during C-DRX On-Duration periodsaccording to the readjusted SPS transmit periodicity (910).

Embodiments of the present invention may be realized in any of variousforms. For example, in some embodiments, the present invention may berealized as a computer-implemented method, a computer-readable memorymedium, or a computer system. In other embodiments, the presentinvention may be realized using one or more custom-designed hardwaredevices such as ASICs. In other embodiments, the present invention maybe realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE) may be configured to includea processor (or a set of processors) and a memory medium, where thememory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

The invention claimed is:
 1. An apparatus comprising: a non-transitorymemory element storing information; and a processing element coupled tothe non-transitory memory element and configured to use at least aportion of the information to cause a wireless communication device to:adjust a semi persistent scheduling (SPS) transmit periodicity withrespect to an SPS activation command and an SPS interval for wirelesscommunications of the wireless communication device via connected-modediscontinuous reception (C-DRX) and SPS; schedule data transmission fora first C-DRX On-Duration period to begin after a first time delayrelative to a beginning of the first C-DRX On-Duration period; andschedule data transmission for one or more respective C-DRX On-Durationperiods subsequent to the first C-DRX On-Duration period, wherein eachrespective data transmission for a corresponding C-DRX On-Durationperiod of the one or more respective C-DRX On-Duration periods isscheduled to begin after a respective time delay relative to a beginningof the corresponding C-DRX On-Duration period, wherein the respectivetime delay is determined according to the adjusted SPS transmitperiodicity and is different from the first time delay; wherein thefirst C-DRX On-Duration period and the one or more respective C-DRXOn-Duration periods correspond to the SPS activation command.
 2. Theapparatus of claim 1, wherein the processing element is furtherconfigured to cause the wireless communication device to adjust the SPStransmit periodicity to enable data transmission to begin as soon as thewireless communication device wakes up during the one or more respectiveC-DRX On-Duration periods.
 3. The apparatus of claim 1, wherein theprocessing element is configured to cause the wireless communicationdevice to schedule the data transmission for the first C-DRX On-Durationperiod to begin following a specified number of subframes subsequent toreceiving the SPS activation command.
 4. The apparatus of claim 1,wherein the processing element is further configured to cause thewireless communication device to readjust the SPS transmit periodicityaccording to: the adjusted SPS transmit periodicity; and an SPSActivation Offset value with respect to a first subframe of one of theone or more respective C-DRX On-Duration periods.
 5. The apparatus ofclaim 4, wherein the processing element is further configured to causethe wireless communication device to use an offset value received duringthe wireless communications of the wireless communication device.
 6. Theapparatus of claim 5, wherein the processing element is furtherconfigured to cause the wireless communication device to receive the SPSActivation Offset value via higher layer signaling.
 7. A non-transitorymemory element storing programming instructions executable by aprocessing element to cause a wireless communication device to: adjust asemi persistent scheduling (SPS) transmit periodicity with respect to anSPS activation command and SPS interval; establish wirelesscommunications via a wireless link, using connected-mode discontinuousreception (C-DRX) and SPS; transmit data during a first C-DRXOn-Duration period, beginning data transmission after a first time delayrelative to a beginning of the first C-DRX On-Duration period; andtransmit data during one or more respective C-DRX On-Duration periodssubsequent to the first C-DRX On-Duration period, beginning each datatransmission after a respective time delay relative to a beginning ofthe respective C-DRX On-Duration period, wherein the respective timedelay is determined according to the adjusted SPS transmit periodicityand is different from the first time delay; wherein the first C-DRXOn-Duration period and the one or more respective C-DRX On-Durationperiods correspond to the SPS activation command.
 8. The non-transitorymemory element of claim 7, wherein the programming instructions arefurther executable by the processing element to cause the wirelesscommunication device to: begin transmitting data during each respectiveC-DRX On-Duration period of the one or more respective C-DRX On-Durationperiods as soon as the wireless communication device wakes up during therespective C-DRX On-Duration period.
 9. The non-transitory memoryelement of claim 7, wherein the programming instructions are furtherexecutable by the processing element to cause the wireless communicationdevice to: begin transmitting data following a specified number ofsubframes after reception of the SPS activation command, during thefirst C-DRX On-Duration period.
 10. The non-transitory memory element ofclaim 7, wherein the programming instructions are further executable bythe processing element to cause the wireless communication device to:readjust the SPS transmit periodicity according to: the adjusted SPStransmit periodicity; and an SPS Activation Offset value with respect toa first subframe of one of the one or more respective C-DRX On-Durationperiods.
 11. The non-transitory memory element of claim 10, wherein theprogramming instructions are further executable by the processingelement to cause the wireless communication device to receive the SPSActivation Offset value via the wireless link.
 12. The non-transitorymemory element of claim 11, wherein the programming instructions arefurther executable by the processing element to cause the wirelesscommunication device to receive the SPS Activation Offset value throughhigher layer signaling.
 13. A wireless communication device comprising:radio circuitry configured to facilitate communications of the wirelesscommunication device via a wireless link; and a processing elementcoupled to the radio circuitry and configured to interoperate with theradio circuitry to cause the wireless communication device to: adjust asemi persistent scheduling (SPS) transmit periodicity with respect to anSPS activation command and an SPS interval for wireless communicationsof the wireless communication device conducted over the wireless linkaccording to connected-mode discontinuous reception (C-DRX) and SPS;schedule data transmission for a first C-DRX On-Duration period to beginafter a first time delay relative to a beginning of the first C-DRXOn-Duration period; and schedule data transmission for one or morerespective C-DRX On-Duration periods subsequent to the first C-DRXOn-Duration period, wherein each respective data transmission for acorresponding C-DRX On-Duration period of the one or more respectiveC-DRX On-Duration periods is scheduled to begin after a respective timedelay relative to a beginning of the corresponding C-DRX On-Durationperiod, wherein the respective time delay is determined according to theadjusted SPS transmit periodicity and is different from the first timedelay; wherein the first C-DRX On-Duration period and the one or morerespective C-DRX On-Duration periods correspond to the SPS activationcommand.
 14. The wireless communication device of claim 13, wherein atleast in response to having adjusted the SPS transmit periodicity, theprocessing element is configured to further interoperate with the radiocircuitry to cause the wireless communication device to enable datatransmission to begin as soon as the wireless communication device wakesup during each of the one or more respective C-DRX On-Duration periods.15. The wireless communication device of claim 13, wherein theprocessing element is configured to further interoperate with the radiocircuitry to cause the wireless communication device to schedule thedata transmission for the first C-DRX On-Duration period to beginfollowing a specified number of subframes subsequent to reception of theSPS activation command.
 16. The wireless communication device of claim13, wherein the processing element is configured to further interoperatewith the radio circuitry to cause the wireless communication device toreadjust the SPS transmit periodicity according to: the adjusted SPStransmit periodicity; and an SPS Activation Offset value with respect toa first subframe of one of the one or more respective C-DRX On-Durationperiods.
 17. The wireless communication device of claim 16, wherein theprocessing element is configured to further interoperate with the radiocircuitry to cause the wireless communication device to use an offsetvalue received via the wireless link as the Activation Offset value. 18.The wireless communication device of claim 17, wherein the processingelement is configured to further interoperate with the radio circuitryto cause the wireless communication device to receive the SPS ActivationOffset value via higher layer signaling.
 19. The wireless communicationdevice of claim 13, wherein the processing element is configured tofurther interoperate with the radio circuitry to cause the wirelesscommunication device to: for each respective SPS activation command of aplurality of SPS activation commands: schedule data transmission for arespective first C-DRX On-Duration period to begin after a respectivefirst time delay relative to a beginning of the respective first C-DRXOn-Duration period; and schedule data transmission for one or moreadditional C-DRX On-Duration periods subsequent to the respective firstC-DRX On-Duration period, wherein each additional data transmission fora corresponding C-DRX On-Duration period of the one or more additionalC-DRX On-Duration periods is scheduled to begin after a respective timedelay relative to a beginning of the corresponding C-DRX On-Durationperiod, wherein the respective time delay is determined according to theadjusted SPS transmit periodicity and is different from the respectivefirst time delay; wherein the respective first C-DRX On-Duration periodand the one or more additional C-DRX On-Duration periods correspond tothe respective SPS activation command.
 20. The wireless communicationdevice of claim 19, wherein the processing element is configured tofurther interoperate with the radio circuitry to cause the wirelesscommunication device to: for each respective SPS activation command ofthe plurality of SPS activation commands: readjust the SPS transmitperiodicity according to: the adjusted SPS transmit periodicity; and anSPS Activation Offset value with respect to a first subframe of one ofthe one or more additional C-DRX On-Duration periods.